Connect with us


Recreating the Intense Conditions of the Earth’s Mantle Solves A Long-standing Geological Mystery





inner earth

The various layers of the inner Earth. (Credit: Ellen Bronstayn/Shutterstock)

Science is never exactly easy, but it’s especially tough when you can’t see, touch or even really interact with your subject. Consider the plight of a geophysicist interested in the makeup and structure of Earth’s interior. Without being able to dig up a sample of our planet’s ultrahot, ultra-pressurized mantle, how can they figure out what makes our planet work?

The answer, in part, is seismic waves. When the ground shakes, as in an earthquake, the vibrations go through and interact with all the materials in their way. This can provide scientists with a means of imaging all those materials, allowing them to virtually peer beneath the surface.

But sometimes that’s not enough. If the models tell you the vibrations — analogous to sound waves in some cases — should travel at a certain speed, but the data show they don’t, you’re left with an anomaly. Something’s wrong, but without somehow recreating the incredible conditions hundreds of miles below the surface, how can you figure out what?

Just such an issue has been plaguing geophysicists studying the Earth’s innards, who’ve noticed that vibrations from earthquakes traveling through the mantle have been going slower than they should be.

At least until now, that is. According to a Nature paper this week, a team of Japanese scientists figured out what was wrong just by recreating those crazy conditions after all.

Mantle Pieces

Their work all comes down to a specific mineral, calcium silicate (CaSiO3) arranged in what’s called a perovskite structure. Scientists refer to this as calcium silicate perovskite, or simply CaPv. This mineral is a major part of Earth’s mantle, the vast region between surface and the inner core.

The mantle itself is divided into the upper and lower, and the boundary between the two, around 410 miles down, is still somewhat mysterious to scientists. That’s where they’d been finding some of these anomalous velocities for traveling sound waves. One idea was maybe the reason the measurements weren’t lining up with the models was because they didn’t fully understand how the CaPv behaved within the mantle. But it’s hard to know for sure if that’s the case, because in those infernally hot temperatures, CaPv takes on a cubic structure, which breaks down into other forms at temperatures below about 600 kelvin.

As the authors put it, “Despite its importance, no measurements of sound velocities have been made in cubic CaPv at high temperature, because this phase is unquenchable at ambient conditions and hence there is no adequate sample for such measurements.”

So, basically, they just made some.

Mineral Madness

The researchers synthesized some cubic CaPv from a glass rod, and kept it at temperatures up to 1700 K and pressures of up to 23 billion pascal (for reference, standard air pressure is 101,000 pascal). The mineral maintained its cubic form in these extreme conditions, allowing the team to run ultrasonic sound velocity measurements.

They found that the material really doesn’t behave the way the theories had predicted: CaPv is about 26 percent less rigid than expected, so sound waves would in fact travel more slowly through it than expected — just as had been observed.

Not only does the finding resolve the conflict between mantle models and experimental data, but it also supports another intriguing idea: This region between the upper and lower mantle may be home to subducted oceanic crust — parts of the ocean floor forced into the mantle — rife with CaPv.

“These results could contribute to our understanding of the existence and behavior of subducted crust materials in the deep mantle,” the authors write, and they also suggest new research avenues for directly measuring the velocity of seismic waves through mantle materials.

Slowly but surely, scientists are figuring out better ways to look at and understand the invisible depths beneath Earth’s surface.


Source link

قالب وردپرس


Globe Climate: Canada’s resource reckoning is coming





Good afternoon, and welcome to Globe Climate, a newsletter about climate change, environment and resources in Canada.

This afternoon, the Alberta government announced that it is restoring a coal mining policy it revoked last spring. At the time, the move provoked a widespread public backlash detailed by The Globe. The original decision, which opened up more than 1.4 million hectares to exploration, was made without public consultation. Premier Jason Kenney previously defended the changes.

Lots more on coal and Canada’s resources industry in this week’s newsletter edition.

Now, let’s catch you up on other news.

Continue Reading


‘Incredibly destructive’: Canada’s Prairies to see devastating impact of climate change





As the climate continues to warm at an alarming rate, experts warn if dramatic steps to mitigate global warming are not taken, the effects in Canada’s Prairie region will be devastating to the country’s agriculture sector.

According to Environment and Climate Change Canada, the country is warming, on average, about double the global rate.

Scientists with the National Oceanic and Atmospheric Administration in the U.S. recently found 2020 was earth’s second-hottest year on record, with the average land and ocean surface temperature across the globe at 0.98 of a degree C above the 20th-century average.

However, the agency found the northern hemisphere saw its hottest year on record, at 1.28 degrees C above the average.

“(In Canada) we are looking at about 6.4C degrees of warming this century, which isn’t much less than one degree per decade, which is just a terrifying rate of warming,” Darrin Qualman, the director of climate crisis policy and action at the National Farmer’s Union said.

Qualman said there is “massive change coming” to Canada’s Prairies, which will be “incredibly destructive.”

“It’s not going too far to say that if we made that happen, parts of the Prairies wouldn’t be farmable anymore,” he said.

According to the federal government, in 2018 Canada’s agriculture and agri-food system generated $143 billion, accounting for 7.4 per cent of the country’s GDP.

The sector employed 2.3 million people in 2018. The majority of the 64.2 million hectares of farmland in Canada is concentrated in the Prairies and in southern Ontario.

The effects of climate change are already being felt on the ground in the Prairies, Qualman said, adding that the NFU has already heard from farmers complaining of “challenging weather.”

“People are sharing pictures of flattened crops and buildings, et cetera, that have been damaged,” he said. “And we’re still at the beginning of this.”

Continue Reading


Insect-based dog food aims to cut your pet’s carbon pawprint





Meat has an enormous carbon footprint, with livestock liable for about 15 per cent of worldwide emissions, as we have beforehand mentioned on this e-newsletter. That is prompted specialists to suggest consuming much less meat for sustainability (and well being) causes.

However what about your pet? One research discovered that the methane and nitrous oxide emissions generated by canine and cat meals within the U.S. alone had been equal to about 64 million tonnes of CO2, or roughly the quantity produced by 13.6 million automobiles. And it might be getting worse, with a development towards feeding pets “human-grade” meat.

That is prompted some pet meals makers to look to lower-carbon protein sources — together with bugs.

Research present that producing insect-based meals requires far much less feed, land and water and generates far fewer greenhouse fuel emissions per kilogram than meats comparable to beef, pork or rooster.

That is one of many causes increasingly more pet meals containing insect protein are hitting the market. Purina, a model owned by multinational Nestlé, launched a line of canine and cat meals containing black soldier fly larvae in Switzerland in November.

In Canada, Montreal-based Wilder Harrier began promoting canine treats made with cricket protein in 2015 and pet food made with black soldier fly larvae in 2019. It plans to broaden to launch a line of insect-based cat treats later this yr and cat meals in 2022 due to “a ton of demand,” mentioned firm co-founder Philippe Poirier.

Wilder Harrier initially labored with animal nutritionists on insect-based merchandise to unravel a unique downside — specifically, the founders’ canines had allergy symptoms to frequent meats utilized in canine meals. Poirier mentioned now about half its prospects hunt down the product due to their pets’ allergy symptoms and about half for environmental causes.

Dr. Cailin Heinze, a U.S.-based veterinary nutritionist licensed by the American School of Veterinary Vitamin, has written concerning the environmental influence of pet meals. She mentioned we’re typically “not as involved as we probably ought to [be]” concerning the environmental footprint of pets.

Alternatively, she famous that the longer-term influence of newer diets, comparable to vegan meals and people containing bugs, hasn’t been nicely examined in comparison with conventional pet meals.

Maria Cattai de Godoy, an assistant professor of animal sciences on the College of Illinois who research novel proteins for pet meals (together with bugs, yeast and plant-based substances), mentioned such substances are rigorously examined to find out their security and diet earlier than being added to pet meals. 

“This can be a very extremely regulated trade,” she mentioned, however admitted it is also evolving.

Relating to bugs, she mentioned constructive information “reveals promise in direction of utilizing them increasingly more in pet meals.” Insect-based proteins have additionally earned the endorsement of the British Veterinary Affiliation, which says some insect-based meals could also be higher for pets than prime steak.

However Godoy famous that there isn’t any one-size-fits-all resolution, and pet homeowners ought to take into consideration the wants of their very own particular person pet and analysis whether or not a specific weight loss plan can be appropriate.

She mentioned that other than the kind of protein, issues like packaging and manufacturing strategies may also make a distinction. For instance, utilizing meat byproducts that may in any other case turn into waste would not drive elevated meat manufacturing the identical approach as utilizing human-grade meat.

Continue Reading